diff options
Diffstat (limited to 'util/mkelfImage/linux-i386/head.S')
| -rw-r--r-- | util/mkelfImage/linux-i386/head.S | 476 |
1 files changed, 476 insertions, 0 deletions
diff --git a/util/mkelfImage/linux-i386/head.S b/util/mkelfImage/linux-i386/head.S new file mode 100644 index 0000000000..c3990ac801 --- /dev/null +++ b/util/mkelfImage/linux-i386/head.S @@ -0,0 +1,476 @@ +/* + * exec_kernel/user_space/head.S + * + * Copyright (C) 2000, 2002, 2003 Eric Biederman + * + * Parts of this code were take from the linux startup + * code of linux-2.4.0-test9 + * + * Other parts were taken from etherboot-5.0.5 + */ + +#define ASSEMBLY 1 + +#define RELOC 0x10000 +#define PROT_CODE_SEG 0x10 +#define PROT_DATA_SEG 0x18 +#define REAL_CODE_SEG 0x08 +#define REAL_DATA_SEG 0x20 + + .equ CR0_PE,1 + +.text +.code32 + + +#include "convert.h" + + .globl startup_32 +startup_32: + cld + cli + + # Save the arguments safely out of the way + movl %eax, boot_type + movl %ebx, boot_data + cmp $0,%esp + jz 1f + movl 4(%esp), %eax + movl %eax, boot_param +1: + + movl stack_start, %esp + + # Clear eflags + pushl $0 + popfl + + # Clear BSS + xorl %eax,%eax + movl $ _edata,%edi + movl $ _end,%ecx + subl %edi,%ecx + cld + rep + stosb + + # Move the gdt where Linux will not smash it during decompression + movl $gdt, %esi + movl $GDTLOC, %edi + movl $(gdt_end - gdt), %ecx + rep movsb + + # Linux makes stupid assumptions about the segments + # that are already setup, so setup a new gdt & ldt + # and then reload the segment registers. + + lgdt gdt_48 + lidt idt_48 + + # Load the data segment registers + movl $ PROT_DATA_SEG, %eax + movl %eax, %ds + movl %eax, %es + movl %eax, %fs + movl %eax, %gs + movl %eax, %ss + + pushl $image_params # image build time parameters as forth arg + pushl boot_param # boot_param pointer as third arg + pushl boot_data # boot data pointer as second arg + pushl boot_type # boot data type as first argument + call convert_params + + movl %eax, %esi # put the real mode pointer in a safe place + addl $16, %esp # pop the arguments + + + # Setup the registers before jumping to linux + + + # clear eflags + pushl $0 + popfl + + # Flag to indicate we are the bootstrap processor + xorl %ebx, %ebx + + # Clear the unspecified registers for good measure + xorl %eax, %eax + xorl %ecx, %ecx + xorl %edx, %edx + xorl %edi, %edi + xorl %esp, %esp + xorl %ebp, %ebp + + + # Jump to the linux kernel + ljmp $ PROT_CODE_SEG , $ 0x100000 + + + /* Routines to query the BIOS... */ + + +/************************************************************************** +E820_MEMSIZE - Get a listing of memory regions +**************************************************************************/ +#define SMAP 0x534d4150 + .globl meme820 +meme820: + pushl %ebp + movl %esp, %ebp + pushl %ebx + pushl %esi + pushl %edi + movl 8(%ebp), %edi /* Address to return e820 structures at */ + subl $RELOC, %edi + movl 12(%ebp), %esi /* Maximum number of e820 structurs to return */ + pushl %esi + call _prot_to_real + .code16 + xorl %ebx, %ebx +jmpe820: + movl $0xe820, %eax + movl $SMAP, %edx + movl $20, %ecx + /* %di was setup earlier */ + int $0x15 + jc bail820 + + cmpl $SMAP, %eax + jne bail820 + +good820: + /* If this is useable memory, we save it by simply advancing %di by + * sizeof(e820rec) + */ + decl %esi + testl %esi,%esi + jz bail820 + + addw $20, %di +again820: + cmpl $0, %ebx /* check to see if %ebx is set to EOF */ + jne jmpe820 + +bail820: + data32 call _real_to_prot + .code32 + popl %eax + subl %esi, %eax /* Compute how many structure we read */ + + /* Restore everything else */ + popl %edi + popl %esi + popl %ebx + movl %ebp, %esp + popl %ebp + ret + + +/************************************************************************** +MEME801 - Determine size of extended memory +**************************************************************************/ + .globl meme801 +meme801: + pushl %ebx + pushl %esi + pushl %edi + call _prot_to_real + .code16 + + stc # fix to work around buggy + xorw %cx,%cx # BIOSes which dont clear/set + xorw %dx,%dx # carry on pass/error of + # e801h memory size call + # or merely pass cx,dx though + # without changing them. + movw $0xe801,%ax + int $0x15 + jc e801absent + + cmpw $0x0, %cx # Kludge to handle BIOSes + jne e801usecxdx # which report their extended + cmpw $0x0, %dx # memory in AX/BX rather than + jne e801usecxdx # CX/DX. The spec I have read + movw %ax, %cx # seems to indicate AX/BX + movw %bx, %dx # are more reasonable anyway... + +e801usecxdx: + andl $0xffff, %edx # clear sign extend + shll $6, %edx # and go from 64k to 1k chunks + movl %edx, %eax # store extended memory size + andl $0xffff, %ecx # clear sign extend + addl %ecx, %eax # and add lower memory into + + jmp e801out +e801absent: + xorl %eax,%eax + +e801out: + data32 call _real_to_prot + .code32 + /* Restore Everything */ + popl %edi + popl %esi + popl %ebx + ret + +/************************************************************************** +MEM88 - Determine size of extended memory +**************************************************************************/ + .globl mem88 +mem88: + pushl %ebx + pushl %esi + pushl %edi + call _prot_to_real + .code16 + + movb $0x88, %ah + int $0x15 + andl $0xffff, %eax + + data32 call _real_to_prot + .code32 + + /* Restore Everything */ + popl %edi + popl %esi + popl %ebx + ret + + +/************************************************************************** +BASEMEMSIZE - Get size of the conventional (base) memory +**************************************************************************/ + .globl basememsize +basememsize: + call _prot_to_real + .code16 + int $0x12 + movw %ax,%cx + DATA32 call _real_to_prot + .code32 + movw %cx,%ax + ret + +/************************************************************************** +_REAL_TO_PROT - Go from REAL mode to Protected Mode +**************************************************************************/ + .globl _real_to_prot +_real_to_prot: + .code16 + cli + cs + addr32 lgdt gdt_48 - RELOC + movl %cr0,%eax + orl $CR0_PE,%eax + movl %eax,%cr0 /* turn on protected mode */ + + /* flush prefetch queue, and reload %cs:%eip */ + data32 ljmp $PROT_CODE_SEG,$1f +1: + .code32 + /* reload other segment registers */ + movl $PROT_DATA_SEG,%eax + movl %eax,%ds + movl %eax,%es + movl %eax,%ss + addl $RELOC,%esp /* Fix up stack pointer */ + xorl %eax,%eax + movl %eax,%fs + movl %eax,%gs + popl %eax /* Fix up return address */ + addl $RELOC,%eax + pushl %eax + + /* switch to protected mode idt */ + cs + lidt idt_48 + ret + +/************************************************************************** +_PROT_TO_REAL - Go from Protected Mode to REAL Mode +**************************************************************************/ + .globl _prot_to_real +_prot_to_real: + .code32 + popl %eax + subl $RELOC,%eax /* Adjust return address */ + pushl %eax + subl $RELOC,%esp /* Adjust stack pointer */ + ljmp $REAL_CODE_SEG,$1f- RELOC /* jump to a 16 bit segment */ +1: + .code16 + /* clear the PE bit of CR0 */ + movl %cr0,%eax + andl $0!CR0_PE,%eax + movl %eax,%cr0 + + /* make intersegment jmp to flush the processor pipeline + * and reload %cs:%eip (to clear upper 16 bits of %eip). + */ + data32 ljmp $(RELOC)>>4,$2f- RELOC +2: + /* we are in real mode now + * set up the real mode segment registers : %ds, $ss, %es + */ + movw %cs,%ax + movw %ax,%ds + movw %ax,%es + movw %ax,%ss + movw %ax,%fs + movw %ax,%gs + + /* Switch to the real mode idt */ + cs + addr32 lidt idt_real - RELOC + + sti + data32 ret /* There is a 32 bit return address on the stack */ + .code32 + +boot_type: .long 0 +boot_data: .long 0 +boot_param: .long 0 + +idt_real: + .word 0x400 # idt limit = 256 + .word 0, 0 +idt_48: + .word 0 # idt limit = 0 + .word 0, 0 # idt base = 0L +gdt_48: + .word gdt_end - gdt - 1 # gdt limit=40, + # (5 GDT entries) + .long GDTLOC # gdt base + +# Descriptor tables +# These need to be in a seperate section so I can be +# certain later activities dont stomp them +gdt: + /* 0x00 */ + .word 0, 0, 0, 0 # dummy + + /* 0x08 */ + /* 16 bit real mode code segment */ + .word 0xffff,(RELOC&0xffff) + .byte (RELOC>>16),0x9b,0x00,(RELOC>>24) + + /* 0x10 */ + .word 0xFFFF # 4Gb - (0x100000*0x1000 = 4Gb) + .word 0 # base address = 0 + .word 0x9A00 # code read/exec + .word 0x00CF # granularity = 4096, 386 + # (+5th nibble of limit) + + /* 0x18 */ + .word 0xFFFF # 4Gb - (0x100000*0x1000 = 4Gb) + .word 0 # base address = 0 + .word 0x9200 # data read/write + .word 0x00CF # granularity = 4096, 386 + # (+5th nibble of limit) + + /* 0x20 */ + /* 16 bit real mode data segment */ + .word 0xffff,(RELOC&0xffff) + .byte (RELOC>>16),0x93,0x00,(RELOC>>24) + + /* For 2.5.x the kernel segments have moved */ + + /* 0x28 dummy */ + .quad 0 + + /* 0x30 dummy */ + .quad 0 + /* 0x38 dummy */ + .quad 0 + /* 0x40 dummy */ + .quad 0 + /* 0x48 dummy */ + .quad 0 + /* 0x50 dummy */ + .quad 0 + /* 0x58 dummy */ + .quad 0 + + + /* 0x60 */ + .word 0xFFFF # 4Gb - (0x100000*0x1000 = 4Gb) + .word 0 # base address = 0 + .word 0x9A00 # code read/exec + .word 0x00CF # granularity = 4096, 386 + # (+5th nibble of limit) + + /* 0x68 */ + .word 0xFFFF # 4Gb - (0x100000*0x1000 = 4Gb) + .word 0 # base address = 0 + .word 0x9200 # data read/write + .word 0x00CF # granularity = 4096, 386 + # (+5th nibble of limit) +/* + * The layout of the per-CPU GDT under Linux: + * + * 0 - null + * 1 - reserved + * 2 - reserved + * 3 - reserved + * + * 4 - default user CS <==== new cacheline + * 5 - default user DS + * + * ------- start of TLS (Thread-Local Storage) segments: + * + * 6 - TLS segment #1 [ glibc's TLS segment ] + * 7 - TLS segment #2 [ Wine's %fs Win32 segment ] + * 8 - TLS segment #3 + * 9 - reserved + * 10 - reserved + * 11 - reserved + * + * ------- start of kernel segments: + * + * 12 - kernel code segment <==== new cacheline + * 13 - kernel data segment + * 14 - TSS + * 15 - LDT + * 16 - PNPBIOS support (16->32 gate) + * 17 - PNPBIOS support + * 18 - PNPBIOS support + * 19 - PNPBIOS support + * 20 - PNPBIOS support + * 21 - APM BIOS support + * 22 - APM BIOS support + * 23 - APM BIOS support + */ +gdt_end: + + + + .section ".trailer", "a" + /* Constants set at build time, these are at the very end of my image */ + .balign 16 + .global image_params +image_params: + +convert_magic: + .long CONVERT_MAGIC +gdt_size: + .long gdt_end - gdt +bss_size: + .long bss_size +ramdisk_flags: + .word 0 +root_dev: + .word DEFAULT_ROOT_DEV +entry: + .long 0 +initrd_start: + .long 0 +initrd_size: + .long 0 +cmdline: + .asciz "BOOT_IMAGE=head.S console=ttyS0 ip=dhcp root=/dev/nfs" + .org cmdline + CMDLINE_MAX, 0 +cmdline_end: |